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https://issues.apache.org/jira/browse/QPID-1101?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12634341#action_12634341
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Rob Godfrey commented on QPID-1101:
-----------------------------------
In the trunk code on Apache the intent is to leave the ArrayLists referenced by
the Index objects immutable, and thus safe to be returned. If an addition or
removal from the bindings is made, a copy of the list is created and
re-inserted into the Index which should remove the need for a copy to be made
on each route operation (the reasoning being that route() is *far* more common
that adding or removing a binding - so you want to move the expense of the
array copy there). Since the size of the arraylist of queues that a message is
being routed to should therefore never change between incrementing the ref
count and placing on the queue I am surprised this is the issue that is you are
seeing with the BDB store. Can you explain in more detail the scenario you are
witnessing?
> DestNameExchange uses shallow copy of queues for routing, causing routing to
> fail if queueDeleted.
> --------------------------------------------------------------------------------------------------
>
> Key: QPID-1101
> URL: https://issues.apache.org/jira/browse/QPID-1101
> Project: Qpid
> Issue Type: Bug
> Components: Java Broker
> Affects Versions: M2, M2.1
> Reporter: Martin Ritchie
> Assignee: Martin Ritchie
> Fix For: M3
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> Summary:
> When testing with the BDBStore module it was noted that on occasion a mesage
> would be enqueued on a queue but the Metadata was not in the DB.
> This is due to the the fact that when routing takes place a shallow copy of
> queues the message has been enqueued to is returned by the DestNameExchange.
> If the queue is deleted before the message can be routed then it is removed
> from the list and never routed. This results in the message being purged from
> the DB but the enqueued reference remaining.
> The solution is to make a deep copy so that the DestNameExchange can modify
> the list without affecting routing.
> Steps to Reproduce:
> This is a race condition so can be difficult but:
> Using the broker with the BDBStore Module.
> Set up a client that reads from queue1 and replies to the JMSReplyTo.
> Set up client2 that reads from a tempQueue.
> Use client2 to send two messages (with tempQueue as the replyTo) to queue1
> When you receive message 1 on client2 close the consumer
> If this is running inVM then the consumer close should occur as message 2 is
> routing.
> Restart the broker and it should fail to start with a MetaData not found for
> message 5 error.
> Defect Identification:
> As above, the shallow copy of enqueued queues is being modifed during routing.
> Proposed Changes:
> Make a copy of the list
> Swap this:
> payload.enqueue(queues);
> to
> payload.enqueue(new ArrayList<AMQQueue>(queues));
> Test Strategy:
> QueueDeleteRouteTest to be provided
> This must be done on trunk then back merged.
> Difficulties exist as the trunk now uses QpidTestCase which is not capable of
> running multiple InVM brokers
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